First questions:
What shipping company would send Captain, crew, ship and cargo into an area of known piracy without the means to protect itself?
What captain of a ship would venture into those waters without the means to repel borders and do his duty as Captain to protect ship, cargo and crew, not necessarily in that order.
What crew man would allow himself to be on a ship in those waters, without the means to protect ship cargo and crew?
Being pirates, they probably don’t view themselves as bound by UN treaties on ship armaments.
And we have a wide array of arms to choose from, depending on the statement we wish to make.
But the inaction, or worse paying ransom, is sending a different, more ominous message to the terrorists around the world.
Maersk Lines carries military cargo containers and such shipments often bump other containers for space.